Place pork shoulder in slow cooker. Season with salt and pepper. Pour vinegar around the pork. Cook on low for 12 hours.
Remove pork. Discard bones. Strain off liquid, reserving 2 cups. Shred pork with forks, then return to cooker.
Combine reserved liquid, brown sugar, hot pepper sauce, cayenne, and red pepper flakes. Add to cooker and mix.
Serve on buns. Top with coleslaw.